Feature Article April 16, 2003
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HeronriesA heronry is a collection of rather ungainly-looking nests of herons. Built largely of sticks with a lining of coarse vegetative material, they are usually placed high among the topmost branches of tall trees.
The Great Blue Heron is the species that builds heronries in our area, and there may be a few or dozens of nests in a colony. These colonies are often visible from some distance away until obscured by the leafing out of trees. Unless blown down by the winds, a nest will be used or repaired in successive years. An adult Great Blue Heron stands approximately one meter high and has a wingspan of up to two meters; it weighs just over two kilograms. Males are slightly larger than females, and their bills one to two centimeters longer. Sometimes mistakenly referred to as cranes, herons fly in a stately, slow-measured flight with the neck doubled back against the shoulders, whereas cranes (and we do have cranes in Canada - the Sandhill or the Whooping) fly with their neck straight out.
Arriving back from the south in late March, a pair will begin renovation of an existing nest or build a new nest. The female will lay 3 to 5 eggs, and the eggs are often laid over a period of days, with one to three days between laying. The incubation period is approximately 28 days, and again the timing is staggered, with intervals of a day or two between hatching. For about three weeks after hatching, the female will brood at night, and the male will take over the duties in the daytime, until the chicks have developed sufficiently to maintain body temperature.
As the chicks grow, the efforts of both parents are required to feed both themselves and their offspring. For the most part, the small chicks remain quietly in the nest until a parent returns with a meal. The returning parent will often pause on a nearby branch for five to ten minutes before making its way to the nest and regurgitating its catch of fish. The chicks first appear as fuzzy heads bobbing and weaving above the edge of the nest, and as they grow and become more vocal, they are often heard before being seen. Not all chicks survive. Raccoons may raid the nest, after either eggs or chicks. Sometimes eggs or dead chicks may be found on the ground under the nest - have they fallen or been blown out? If they do survive, by mid-June, some of the chicks are so big it is difficult to differentiate them from adults, but they may be identified by a line of dark feathers sticking straight up on the head, or the fluffy but plume-less breasts. The chicks will practice flying, jumping short distances and flapping their large wings until they fledge.
Alert and wary, if the colony is disturbed by human activity, it may be deserted. Under federal legislation, the nests, eggs, young and adults are protected throughout the year, both in Canada and the United States. Enjoy this picturesque bird!
Call me with your observations: 268-2518.
